Self-cleaning ovens clean by heating the oven above normal cooking temperatures to burn off and eliminate the residues created in the oven during normal cooking. The organic cooking residues oxidize and evolve as smoke and vapors, which comprise volatile organic compounds (VOCs) and particulate matter. Standard commercially-available ovens include catalytic converters. These catalytic converters complete the oxidation process, converting the evolved smoke and vapors into carbon dioxide and water, thereby preventing smoke and odors from escaping into the kitchen during the self-cleaning cycle.
Standard catalytic converters for self-cleaning ovens normally include a catalyst coated ceramic honeycomb-shaped disk. These coated ceramic disks are positioned within the oven's exhaust conduit or vent, through which the hot smoke and VOCs pass. The disks, typically 1¼″ to 2″ in diameter and ½″ thick, are mounted in a flanged, cylindrical metal tube (or can), roughly 1″ to 5″ long, with impingement-crimped restraints on both sides of the disk. A metal sealing ring optionally is provided around the top circumference of the ceramic disk, forming a seal between the interior wall surface of the metal tube and the outer circumferential surface of the ceramic disk, to reduce gas bypass. The sealing ring also protects the ceramic disk from fracture during the crimping process, as the ring is interposed between the top surface of the ceramic disk and the notches of the impingement-crimped restraints. The flanged tube, which serves as at least a portion of the exhaust vent, is then mounted with screws into the kitchen range in communication with the self-cleaning oven. The cylindrical can design, however, does not fit in some designs of kitchen ranges, such as those wherein the exhaust vents have sharp bends or those using “flat”-shaped exhaust vents. In some range or oven designs, the standard cylindrical tube and/or the ½ inch thick disk will not fit. Moreover, installation of the metal can using screws is labor-intensive and costly.
Another design of catalytic converter includes catalyst coated metal screens mounted in a metal tube, much like the ceramic substrate is. The mounting is then attached with screws into an exhaust vent assembly. The coated screens, however, generally are inferior to the coated ceramics, as the screens typically will lose catalyst efficiency after far fewer self-cleaning cycles than the coated ceramics. The problem with the coated screens stems from the mismatch between the thermal expansion of the ceramic-based catalyst coating and the thermal expansion of metal wires, which over repeated thermal cycles leads to peeling off of the coating. A ceramic substrate, in contrast, minimizes the thermal expansion mismatch and would be preferred. Coalescing of the catalytic metals may be another problem with using screens. Thus it would be advantageous to be able to use a ceramic substrate catalyst in a variety of self-cleaning oven applications, particularly those where the exhaust vents are narrow or have sharp bends.
It is therefore an object of the present invention to provide a catalytic converter device including a catalyst-coated ceramic substrate, wherein the device can be easily mounted in a self-cleaning oven, including standard ovens and those ovens having flat shaped exhaust vent tubes.
It is a further object of the present invention to provide methods for installing such catalytic converter devices in an oven without the need for screws.
These and other objects, features, and advantages of the present invention will become apparent upon review of the following detailed description of the invention when taken in conjunction with the drawings and the appended claims.